Foundation
Chemistry Foundation
Valence Electrons and Valency
Question
An atom of an element has 15 electrons in M shell and 2 electrons in N shell. Atomic number of the element will be :
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Solution
The atomic number equals the total number of electrons in a neutral atom. Electrons fill shells in order: K, L, M, N. The K shell holds 2 electrons, L holds 8, and M holds up to 18. Given 15 electrons in the M shell and 2 in the N shell, we must first account for the inner K and L shells.
Total electrons = K shell (2) + L shell (8) + M shell (15) + N shell (2).
So, atomic number =
Final Answer: 27